1. Field of the Invention
This invention relates to a travel speed controller for use in an electrically powered light weight vehicle, and to an electrically powered light weight vehicle. More particularly, this invention relates to a travel speed controller which can control the travel speed of an electrically powered light weight vehicle of the type in which battery-powered motor is used as a prime motor, such as an electrically powered bicycle or an electrically powered wheelchair, and the electrically powered light weight vehicle provided with the controller. The travel speed controller can control the travel speed of the electrically powered light weight vehicle, with no aid of an accelerator nor foot pedals, automatically in such a manner as to substantially reflect an operator""s physical strength or will.
2. Description of the Related Art
There are recently various types of electrically powered light weight vehicles of the type above. Among them, there has been provided a bicycle body of an ordinary type, with a battery and a motor being mounted thereon. Since the fundamental operation of this type of vehicle requires no complicated skill or special knowledge, this type of vehicle has now gained public favor among various generations from children to elder people. Further, since environmental problem, or air pollution is being caused due to exhaust gas from vehicles, the number of user seems to be increasing year by year.
The travel speed of this popular type of vehicle is usually controlled by operating an accelerator device (variable resistor, etc.) or pumping of foot pedals.
In many vehicles of the type, a handle bar grip is used also as an accelerator dial. In these cases, an operator may mistakenly rotate the accelerator dial whereby the vehicle would become out of control, eventually causing serious traffic accident. Such mistake is provided particularly by not-experienced operators. Even though the operators could become more careful, since the human being cannot become perfect, such a wrong operation cannot be exterminated.
As for the case of vehicle in which the pedals also serve as the accelerator, the rotation rate of the motor is controlled based on the result obtained by detecting the rotation rate of pedals. Correspondingly, when reducing the travel speed, the operator is required, not only to apply the brakes to the vehicle, but also to surely stop the rotation of the pedals. Considering the discussion above, controlling the travel speed by such operations as explained above would not been easy against operator""s expectations. Further, during deceleration, unless the main power switch is turned OFF, the motor is still driven corresponding to the travel speed at that time. Correspondingly, the battery power is being consumed at a high rate, and therefore the travel range would be limited.
In the light of problems which have been described as above, an object of the present invention is to provide a travel speed controller for use in an electrically powered light weight vehicle, which, if the controller is provided with the vehicle, can control the travel speed of the vehicle, with no aid of an accelerator nor foot pedals, automatically in such a manner as to substantially reflect an operator""s physical strength or will. Eventually, the vehicle can surely reduces wrong operation, thus reducing traffic accident.
Another object of the present invention is to provide a travel speed controller for use in an electrically powered light weight vehicle, which, if the controller is provided with the vehicle, can surely stop drive of the motor during decceleration, thus saving electric power of battery.
Further, a further object of the present invention is to provide a safe and comfortable electrically powered light weight vehicle provided with the travel speed controller as above discussed.
To achieve the above objects, corresponding to the invention, there is provided, a travel speed controller for use in an electrically powered light weight vehicle comprising: a human riding part, a brake means, a battery-powered motor, a rotation transmission means for transmitting rotation of said motor to a wheel via a free gear, a wheel rotation sensor for outputting a pulse signal in proportion to the rotation rate of said wheel, a brake switch for outputting a signal corresponding to operation of said brake means, and a control circuit for calculating an acceleration based on operation treatment of variation of time intervals of the pulse signal outputted from said wheel rotation sensor and memorizing the acceleration, and supplying to said motor a driving electric current corresponding to the memorized acceleration, said control circuit being adjusted to calculate an acceleration based on operation treatment of variation of time intervals of the pulse signal being outputted from said wheel rotation sensor and, if the calculated acceleration exceeds the memorized acceleration, to renew the memorized acceleration, and being adjusted, if a signal is inputted from said brake switch, to erase the memorized acceleration.
Corresponding to the invention, there is further provided an electrically powered light weight vehicle comprising: a body frame for supporting a plurality of wheels and being provided with a human riding part and a steering means, a motor, a battery for use as a source of electric power to said motor, a rotation transmission means for transmitting rotation of said motor to a wheel via a free gear, a brake means for applying the brakes to rotation of said wheels, and a travel speed controller, said travel speed controller having: a wheel rotation sensor for outputting a pulse signal in proportion to the rotation rate of said wheel, a brake switch for outputting a signal corresponding to operation of said brake means, and a control circuit for calculating an acceleration based on operation treatment of variation of time intervals of the pulse signal outputted from said wheel rotation sensor and memorizing the acceleration, and supplying to said motor a driving electric current corresponding to the memorized acceleration, said control circuit being adjusted to calculate an acceleration based on operation treatment of variation of time intervals of the pulse signal being outputted from said wheel rotation sensor and, if the calculated acceleration exceeds the memorized acceleration, to renew the memorized acceleration, and being adjusted, if a signal is inputted from said brake switch, to erase the memorized acceleration.
With this structure, according to the electrically powered light weight vehicle provided with the travel speed controller as above discussed, an operator pushes ahead of the body of the vehicle, or, upon sitting on a saddle, kicks the ground, similarly when riding on an ordinary bicycle. These actions apply an accelerating force of an intended amount to the vehicle body. Thereby, the motor of the vehicle is actuated at a rotation rate corresponding to the accelerating force. After actuation, the motor is controllably driven at a rotation rate as to have the wheel to be kept at the maximum rotation rate obtained when the accelerating force was being applied.
Then, during travelling, when a further accelerating force is applied to the vehicle body by applying physical power of the operator, for example by kicking the ground, and by traveling along the downhill road, the rotation rate of the motor, or the driving power, is changed corresponding to the further accelerating force to have the wheel to be rotated at the maximum rotation rate obtained when the further accelerating force was being applied.
When the operator applies the brakes during travelling, since supply of the driving power is cut off from the motor, the rotation of the motor is stopped. That is, the travel speed is controlled only by strength of the brakes applied by the operator. During the time, the vehicle is being moved only by inertia. Thereafter, only when any accelerating force is applied again, for example by kicking the ground, the motor is re-actuated and re-driven so as to have the wheel to be rotated. Since the brake is necessarily applied when intentionally stopping the vehicle 1, the motor is stopped and keeps the state unless any accelerating force is applied.
As above discussed, according to the present invention, the human power is required only when actuating and accelerating the vehicle, and these occasions are limited and temporary. In other words, the travel of the vehicle depends on the rotative power of the motor. However, the travel speed is controlled based solely on an operator""s will and physical strength. In particular, when the operator applies the brakes, the reduction rate of the travel speed depends only on the strength of the brakes applied by the operator, and the vehicle is then being moved by inertia. Accordingly, the operator may control the travel speed in the same feeling as that when he controls the travel speed of an ordinary, pedal-motive bicycle. There have been occurred serious traffic accidents of the ordinary electricallypowered light weight vehicle due to unintentional and inappropriate high-speed, such as a sudden movement out of control due to wrong operation of the accelerator device. According to the present invention, however, since there is no acceleration device which must be controlled by the operator himself, the traffic accident due to wrong operation of the accelerator device as above discussed may prevented almost perfectly, and at the same time, since during traveling, the vehicle is moved by driving force of the motor, the operator feels less fatigued than when riding such as a prior-art vehicle described above.
According to the present invention, even during travelling, no driving electric current is supplied to the motor for the period between when the brake is applied and the next accelerating force is applied. Accordingly, the electric power of the battery can be saved, thus the travel range may remarkably be extended.
According to the present invention, since the rotation of the motor is transmitted to the wheel via a free gear (one-way clutch), when the rotative member on the side of the motor as to the free gear, for example a sprocket, is rotated in the rearward direction relative to the wheel, the motor will not make a load against that wheel.
Therefore, when the main power switch of the travel speed controller has been turned OFF, or when the battery has run out, the operator can easily move the vehicle ahead, because the motor makes no load against of the ahead movement. That is, the operator can easily push the vehicle in the same feeling as that of the ordinary foot-pedal type bicycle.
According to the present invention, there is provided a travel speed controller for an electrically powered light weight vehicle as claimed in claim 1, further comprising a circuit with a safety switch in which a contact is closed if a load exceeding a predetermined weight is applied to said human riding part, or in which a contact is opened or closed by operation with hand or foot of an operator, said circuit being adjusted to stop of supply of a driving electric current to said motor under conditions where said contact of said switch is not closed.
With this structure, when an operator unintentionally pushes ahead of the vehicle before he places his body in appropriate position, since no driving electric current is supplied toward the motor, the movement out of control or the falling down of the vehicle may be surely prevented.
The safety switch according to the present invention includes a load switch of which contact is closed and opened by using a pressure-sensitive rubber as an actuator, and any other type of switch of which contact is closed and opened by the operator""s hand-or foot-operation (manual operation switch). When the load switch is used as the safety switch, the load switch may be placed on the saddle or the footstep. When the hand-operating switch is used, the switch may be placed on the grip of the handle bar or in the vicinity thereof. When the foot-operating switch is used, the switch may be placed on the foot step, the kickstand, or in the vicinity thereof.
Although there may be provided only one safety switch, there also may be provided combination of two or more safety switches incorporated in a safety switch circuit. The safety switch circuit maybe connected, in series, between the battery and the main power switch.